The proposed study will assess the relation between total nutrient intake of the antioxidants, vitamin E and vitamin C, and incident Alzheimer's disease in a bi-racial population of 8330 persons 65 years and older living in a geographically-defined community. The East Boston studies provide data suggesting that use of vitamin E and vitamin C may be related to decreased risk of incident Alzheimer's disease. In addition, preliminary data from the Iowa and East Boston EPESE appear to indicate that vitamin E use may result in less decline in cognitive impairment with age. The population-based, longitudinal design of the Iowa and East Boston studies make it unlikely that the results are due to biased estimates; however, the data were restricted to current vitamin supplement use and there were a limited number of supplement users. The proposed study will provide baseline information on total dietary intake as well as current and past use of vitamin supplements for participants in the Chicago Health and Aging Project. The proposed study will test the following hypotheses: (a) Incidence of clinically diagnosed Alzheimer's disease is lower among persons with higher intake of vitamin E. (b) Incidence of clinically diagnosed Alzheimer's disease is lower among persons with higher intake of vitamin C. (c) Intakes of vitamin E and vitamin C are inversely related to decline in cognitive function. In addition, the study will provide a description of nutrient intake in a defined population of older persons, identify predictors of change in nutrient intake over a three-year period, and assess the reliability and validity of nutrient estimates from a food frequency questionnaire. There are three components to the proposed study: 1) the baseline assessment of nutrient intake, cognitive function and other covariates, and prevalent disease in the Chicago Health and Aging Project, an on-going population-based prospective study of incident Alzheimer's disease, 2) the follow-up assessment of changes in nutrient intake and cognitive function, and clinical evaluation of incident Alzheimer's disease three years from baseline, and 3) the conduct of reliability and validity studies on the food frequency method of assessing nutrient intake in the Chicago Health and Aging Project population.